Chapter 6 Amines and Amides Nitrogen-Containing Functional Groups • Nitrogen is in Group V of the periodic table, and in Chapter 6 most of its compounds, it has three single bonds and one lone pair: Amines and Amides N Chapter Objectives: • In this chapter, we will take a look at two functional • Learn to recognize the amine and amide functional groups. • Learn the IUPAC system for naming amines and amides. groups which contain nitrogen atoms connected to • Learn the important physical properties of the amines and amides. carbons: the amines and the amides. • Learn the major chemical reactions of amines and amides, and learn how to predict the O products of amide synthesis and hydrolysis reactions. • Learn some of the important properties of condensation polymers, especially the polyamides. RR''N RCN R' Mr. Kevin A. Boudreaux Angelo State University R' R" CHEM 2353 Fundamentals of Organic Chemistry Amine Amide Organic and Biochemistry for Today (Seager & Slabaugh) www.angelo.edu/faculty/kboudrea 2 Amines • Amines and amides are abundant in nature. They are a major component of proteins and enzymes, nucleic acids, alkaloid drugs, etc. (Alkaloids are N- containing, weakly basic organic compounds; thousands of these substances are known.) • Amines are organic derivatives of ammonia, NH3, in which one or more of the three H’s is replaced by a Classification and carbon group. • Amines are classified as primary (1°), secondary Nomenclature of Amines (2°), or tertiary (3°), depending on how many carbon groups are connected to the nitrogen atom. HHN RHN RHN RR''N H H R' R' Ammonia 1° Amine 2° Amine 3° Amine 3 4 Examples: Classifying Amines Nomenclature of Amines • Classify the following amines as primary (1°), • Simple 1°, 2°, and 3° amines: common (trivial) secondary (2°), or tertiary (3°). names are obtained by alphabetically arranging the names of the alkyl substituents on the nitrogen and H CH3 NH2 adding the suffix -amine (e.g., ethylmethylamine). • Amines in the IUPAC system: the “e” ending of CH3CH2CH2 N H CH3 N CH3 CH3CH2CHCH3 the alkane name for the longest chain is replaced with –amine. The amine group is located by the position number. Groups that are attached to the nitrogen atom are located using “N” as the position H number. More complex primary amines are named with —NH2 as the amino substituent. N CH3CH2 N CH3 N • Aromatic amines: named as derivatives of the NH2 H parent compound aniline. Substituents attached to the nitrogen are indicated by using “N-” as the location number. 5 aniline 6 Chapter 6 Amines and Amides Examples: Nomenclature of Amines Examples: Nomenclature of Amines • Provide common names for the following 2° and 3° • Provide common names for the following 2° and 3° amines; for 1° amines, provide common and/or amines; for 1° amines, provide common and/or IUPAC names where possible. IUPAC names where possible. H NH2 CH3 CH3 NH2 CH3 NCH3 CH3CH2CH2CHCH3 CH3 NCH3 H NH CH 3 CH3CHCH2CH2 NH2 CH3 NCH2CH3 CH3CH2CH2 NH2 CH CH CH CHCH 3 2 2 3 NH2 7 8 Examples: Nomenclature of Amines Examples: Nomenclature of Amines • Provide common names for the following 2° and 3° • Provide names for the following aromatic amines. amines; for 1° amines, provide common and/or IUPAC names where possible. NH CH3 NH2 OH ONH2 NH2 CH3 CH3CCH2CH2CH2CHCH3 CH3 CH3 CH3 CH2CH3 N N 9 10 Examples: Nomenclature of Amines Examples: Nomenclature of Amines • Provide names for the following aromatic amines. • Draw structural formulas for the following molecules: – ethylisopropylamine CH3 CH3 CH3 H N N – tert-butylamine CH3 CH2CH3 CH3 CH3 N – 2-pentanamine CH3CH2 CH3 11 12 Chapter 6 Amines and Amides Examples: Nomenclature of Amines Examples: Nomenclature of Amines • Draw structural formulas for the following molecules: • Draw structural formulas for the following molecules: – N-methyl-2-propanamine – N-methyl-2-chloroaniline – 1,6-diaminohexane – N,3-diethylaniline – 3-amino-1-propanol – N,N-dimethylaniline 13 14 Physical Properties of Amines: H-Bonding • 1° and 2° amines can hydrogen bond to each other: CH3 N H CH3 N CH3 H H H H Physical Properties of CH3 N H N H CH3 N H N CH3 H CH3 CH3 CH3 Amines • 3° amines cannot hydrogen bond to each other: CH3 NCH3 CH3 CH3 X CH3 N CH3X N CH3 15 16 CH3 CH3 Physical Properties of Amines: Boiling Points Physical Properties of Amines: Boiling Points • Nitrogen is less electronegative than oxygen, so the Boiling Point: N—H bond is not quite as polar as the O—H bond. Carboxylic acid – Hydrogen bonds from N—H’s are not as strong Alcohols as those resulting from O—H’s. 1°/2° Amines – Hydrogen bonding between 1° and 2° amines is 3° Amines/Alkanes not as strong as those found in alcohols or carboxylic acids. Molecular Boiling Name weight point • 1° and 2° amines have lower boiling points than alcohols of similar molecular weight. Acetic acid 60.0 g/mol 118°C 1-propanol 60.1 g/mol 97°C • 3° amines, since they do not hydrogen bond to each other, have boiling points similar to hydrocarbons of propyl amine 59.1 g/mol 48°C the same molecular weight. ethylmethylamine 59.1 g/mol 36°C trimethylamine 59.1 g/mol 2.9°C butane 58.1 g/mol -0.5°C 17 18 Chapter 6 Amines and Amides Physical Properties of Amines: Water Solubility Physical Properties of Amines: Odor • 1°, 2°, and 3° amines can all form hydrogen bonds • Low molecular-weight amines tend to have sharp, with water. penetrating odors similar to ammonia • Low-molecular weight amines are generally water- • Higher molecular-weight amines often smell like soluble. rotting fish, and are often found in decaying animal tissues. NH NH H H H 2 2 O O O CH3 N CH3 CH2CH2CH2CH2 CH2CH2CH2CH2CH2 H H H H H CH3 NH2 NH2 CH3 N H O CH3 N H O CH3 N CH3 Trimethylamine 1,4-Diaminobutane 1,5-Diaminopentane H H CH H CH Responsible for the (Putrescine) (Cadaverine) 3 3 odor of rotting fish A poisonous oil present in A poisonous, viscous liquid O rotting flesh; produced present in rotting flesh; HH during the decomposition of produced during the the amino acid arginine; also decomposition of the amino partially responsible for the acid lysine; also partially odor of urine and bad breath responsible for the odor of 19 urine and bad breath 20 Examples: Predicting Physical Properties Examples: Predicting Physical Properties • Arrange the following compounds in order of • Which member of each of the following pairs of increasing boiling point. (All of the compounds compounds would you expect to have a higher have about the same molecular weight.) boiling point? propanoic acid, diethylamine, 1-butanol, – 2-aminopropane or 2-aminohexane ethyldimethylamine – triethylamine or 1-aminohexane – propanoic acid or diethylamine – 1-pentanol or 1-aminopentane 21 22 Important Alkaloids O O CH3 CH3 H CH 3 N H N N N N CH N 3 O N O N N N Nicotene CH 3 CH3 Found in tobacco plants; mild Caffeine Theobromine stimulant in small doses; Found in the seeds of Coffea arabica, Found in the seeds of addictive, but not especially Some Important roasted coffee beans; inhibits the action of Theobroma cacao; the harmful itself phosphodiesterase, an enzyme which stimulating ingredient in inhibits cyclic adenosine monophosphate chocolate. (AMP), which is responsible for forming Alkaloids glucose in the bloodstream CH3 N HO N CH3O N Dextromethorphan Quinine 23 CH3O 24 Ingredient in cough suppressants. Antimalarial drug from cinchona tree Chapter 6 Amines and Amides CH3 CH3 CH3 O O CH2CH3 N O N N H N N CH CH OCH 2 3 3 O CH3O H H N CH H H H N 3 O O O H H O O O OH Melatonin A naturally occuring hormone produced in the pineal gland; its production is triggered by the N absence of light; causes drowsiness in humans H Lysergic acid diethylamide (LSD) at night, triggers birds to migrate, and signals A synthetic hallucinogen from alkaloids obtained OH dogs to shed their winter coats; sold as a from ergot, a fungus which grows on rye Cocaine Atropine treatment for jet lag. The form which is “snorted” relaxes muscles and reduces secretion OH is the hydrochloride salt; the of saliva during surgery; used to Scopolamine Strychnine N free-base “crack” form is dilate pupils for eye examinations. used in treatment of motion N N H A poison from strychnos burned and inhaled, and sickness O reaches the brain in 15 plant (Nux vomica); used H CCH N seconds. 3 3 as a rat and mouse poison HO P N H H O N+ R N OH H N Zephiran chloride OH OH H H (benzalkonium chloride) O O Coniine Antiseptic compound that kills H Inosine Monophosphate (IMP) Poison from hemlock bacteria and fungi on contact With monosodium glutamate (MSG), one of the 25 major substances responsible for the flavor of meat 26 Nitrogen Wastes The disposal of waste nitrogen from the body is a problem which different species of animals have solved in different ways: O H O H OH O NH O N 2 H N NH N 2 HO CH3O CH3 O O O O N N NH2 N N O N O O N H H H H H O O O H Allantoic acid Allantoin N N N Uric acid Marine vertebrates further O Most mammals contain enzymes Birds, reptiles and insects excrete nigrogen metabolyze allantoin into CH3 CH3 CH3 which metabolyze uric acid into wastes in the form of uric acid. Uric acid can allantoic acid.